    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *     http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017
    018package org.apache.commons.configuration2;
    019
    020import org.apache.commons.configuration2.tree.ConfigurationNodeVisitorAdapter;
    021import org.apache.commons.configuration2.tree.NodeHandler;
    022import org.apache.commons.configuration2.tree.NodeTreeWalker;
    023import org.xml.sax.Attributes;
    024import org.xml.sax.helpers.AttributesImpl;
    025
    026/**
    027 * <p>
    028 * A specialized SAX2 XML parser that "parses" hierarchical configuration
    029 * objects.
    030 * </p>
    031 * <p>
    032 * This class mimics to be a SAX conform XML parser. Instead of parsing XML
    033 * documents it processes a {@code Configuration} object and generates SAX
    034 * events for the single properties defined there. This enables the whole world
    035 * of XML processing for configuration objects.
    036 * </p>
    037 * <p>
    038 * The {@code HierarchicalConfiguration} object to be parsed can be specified
    039 * using a constructor or the {@code setConfiguration()} method. This object
    040 * will be processed by the {@code parse()} methods. Note that these methods
    041 * ignore their argument.
    042 * </p>
    043 *
    044 * @version $Id: HierarchicalConfigurationXMLReader.java 1842194 2018-09-27 22:24:23Z ggregory $
    045 * @param <T> the type of the nodes supported by this reader
    046 */
    047public class HierarchicalConfigurationXMLReader<T> extends
    048        ConfigurationXMLReader
    049{
    050    /** Stores the configuration object to be parsed. */
    051    private HierarchicalConfiguration<T> configuration;
    052
    053    /**
    054     * Creates a new instance of {@code HierarchicalConfigurationXMLReader}.
    055     */
    056    public HierarchicalConfigurationXMLReader()
    057    {
    058        super();
    059    }
    060
    061    /**
    062     * Creates a new instance of {@code HierarchicalConfigurationXMLReader} and
    063     * sets the configuration to be parsed.
    064     *
    065     * @param config the configuration object
    066     */
    067    public HierarchicalConfigurationXMLReader(
    068            final HierarchicalConfiguration<T> config)
    069    {
    070        this();
    071        setConfiguration(config);
    072    }
    073
    074    /**
    075     * Returns the configuration object to be parsed.
    076     *
    077     * @return the configuration object to be parsed
    078     */
    079    public HierarchicalConfiguration<T> getConfiguration()
    080    {
    081        return configuration;
    082    }
    083
    084    /**
    085     * Sets the configuration object to be parsed.
    086     *
    087     * @param config the configuration object to be parsed
    088     */
    089    public void setConfiguration(final HierarchicalConfiguration<T> config)
    090    {
    091        configuration = config;
    092    }
    093
    094    /**
    095     * Returns the configuration object to be processed.
    096     *
    097     * @return the actual configuration object
    098     */
    099    @Override
    100    public Configuration getParsedConfiguration()
    101    {
    102        return getConfiguration();
    103    }
    104
    105    /**
    106     * Processes the actual configuration object to generate SAX parsing events.
    107     */
    108    @Override
    109    protected void processKeys()
    110    {
    111        final NodeHandler<T> nodeHandler =
    112                getConfiguration().getNodeModel().getNodeHandler();
    113        NodeTreeWalker.INSTANCE.walkDFS(nodeHandler.getRootNode(),
    114                new SAXVisitor(), nodeHandler);
    115    }
    116
    117    /**
    118     * A specialized visitor class for generating SAX events for a hierarchical
    119     * node structure.
    120     */
    121    private class SAXVisitor extends ConfigurationNodeVisitorAdapter<T>
    122    {
    123        /** Constant for the attribute type. */
    124        private static final String ATTR_TYPE = "CDATA";
    125
    126        /**
    127         * Visits the specified node after its children have been processed.
    128         *
    129         * @param node the actual node
    130         * @param handler the node handler
    131         */
    132        @Override
    133        public void visitAfterChildren(final T node, final NodeHandler<T> handler)
    134        {
    135            fireElementEnd(nodeName(node, handler));
    136        }
    137
    138        /**
    139         * Visits the specified node.
    140         *
    141         * @param node the actual node
    142         * @param handler the node handler
    143         */
    144        @Override
    145        public void visitBeforeChildren(final T node, final NodeHandler<T> handler)
    146        {
    147            fireElementStart(nodeName(node, handler),
    148                    fetchAttributes(node, handler));
    149
    150            final Object value = handler.getValue(node);
    151            if (value != null)
    152            {
    153                fireCharacters(value.toString());
    154            }
    155        }
    156
    157        /**
    158         * Checks if iteration should be terminated. This implementation stops
    159         * iteration after an exception has occurred.
    160         *
    161         * @return a flag if iteration should be stopped
    162         */
    163        @Override
    164        public boolean terminate()
    165        {
    166            return getException() != null;
    167        }
    168
    169        /**
    170         * Returns an object with all attributes for the specified node.
    171         *
    172         * @param node the current node
    173         * @param handler the node handler
    174         * @return an object with all attributes of this node
    175         */
    176        protected Attributes fetchAttributes(final T node, final NodeHandler<T> handler)
    177        {
    178            final AttributesImpl attrs = new AttributesImpl();
    179
    180            for (final String attr : handler.getAttributes(node))
    181            {
    182                final Object value = handler.getAttributeValue(node, attr);
    183                if (value != null)
    184                {
    185                    attrs.addAttribute(NS_URI, attr, attr, ATTR_TYPE,
    186                            value.toString());
    187                }
    188            }
    189
    190            return attrs;
    191        }
    192
    193        /**
    194         * Helper method for determining the name of a node. If a node has no
    195         * name (which is true for the root node), the specified default name
    196         * will be used.
    197         *
    198         * @param node the node to be checked
    199         * @param handler the node handler
    200         * @return the name for this node
    201         */
    202        private String nodeName(final T node, final NodeHandler<T> handler)
    203        {
    204            final String nodeName = handler.nodeName(node);
    205            return (nodeName == null) ? getRootName() : nodeName;
    206        }
    207    }
    208}